Fuel Cap and Filler Neck

ABSTRACT

A fuel cap is disclosed that contains a flexible hemispherical closure member which is substantially compressible and resilient with a form approximating half of a sphere. The circular face of the hemispherical sealing member is coupled to the underside of the fuel cap. Sealing of the fuel tank is obtained where the flexible member contacts the inner surface of the filler neck. The flexible sealing member includes a section of rigid tubing aligned coaxially to the axis of the fuel cap to serve as a vent tube for safety. The vent tube penetrates the flexible sealing member, and the upper portion of the vent tube penetrates the top portion of the cap. Inset into the cap top portion and covering the end of the tube section is a meltout plug. The cap may alternately include a compression washer mounted to the end of the vent tubing, for use with filler necks where the inside circumference contains a ridge. Where the washer contacts the filler neck ridge when the cap is installed, it is pushed up against and compresses the flexible sealing member when installed in the filler neck. The compression of the flexible sealing member provides additional sealing of the fuel cap against the filler neck inside surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. Pat. No. 5,405,040 entitled “Cap for Fuel Inlet” issued on Apr. 11, 1995 and to U.S. Pat. No. 7,303,089 entitled “Anti-siphon Fuel Cap and Filler Tube Assembly” issued on Dec. 4, 2007 both in the name of the same inventor as the present patent application and both incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

FIELD OF THE INVENTION

This invention relates generally to fuel caps for commercial vehicles and, more specifically, to an improved fuel cap which provides an improved seal between the fuel cap and a filler neck to an attached fuel tank.

BACKGROUND OF THE INVENTION

Large trucks and other heavy duty vehicles powered by diesel engines carry fuel in one or more tanks. Fuel is admitted to a fuel tank through a fuel filler neck or tube. The fuel filler neck is normally closed by a cap except when fuel is being added to the tank. Some designs of fuel caps consist of a plastic body with threads that are received onto the open upper end of the fuel filler neck of the vehicle fuel tank. Other designs use a system of lugs and slots to secure the cap. The cap serves an important safety function, and also substantially prevents the release of fuel vapors from the fuel filler neck and tank, which otherwise would be a significant source of hydrocarbon emissions.

There are numerous regulations that apply to the cap in order to minimizing fuel leakage and fire hazards as a result of collision or other accident. One regulation requires testing for safety under a procedure known as the drop test. In the drop test a load is dropped a certain distance onto a cap closing a fuel filler neck of a fuel tank. The fuel cap must continue to maintain an effective seal with the fuel filler neck after the drop.

Another requirement is that the fuel cap must be able to vent high pressure when conditions within a tank caused by high temperatures as in a fire so that more dangerous explosion hazards are minimized.

In U.S. Pat. No. 5,405,040, Keller discloses a fuel cap and fuel filler neck which overcomes the above problems. However, during refueling of the fuel tanks, many people are extremely rough in their handling of placing the fuel nozzle in the inlet of the fuel filler neck. Thus, damage may occur to the lip area of the neck portion of the fuel filler neck. The damage may compromise the seal between the fuel cap and the fuel filler neck.

In U.S. Pat. No. 7,303,089 Keller discloses a fuel cap and anti-siphon fuel fuel filler neck wherein the cap contains a compression coil spring-loaded closure member or diaphragm mounted on the interior top portion to seal and secure the fuel tank and fuel filler neck from fuel leakage and vapor emissions. The design meets the above stated needs and is substantially simpler than other designs that meet the requirements of the drop test. But additional manufacturing cost savings may be obtained with yet simpler designs that, for example, do not incorporate the compression coil spring of the closure member. Additionally, this invention incorporates no specific provisions to vent the contents at elevated pressure caused by elevated temperatures.

Accordingly, there has been a need for a novel improved fuel cap and fuel filler neck assembly which provides robust and simplified construction, is inexpensive to manufacture, and affords an effective seal to meet regulatory requirements. The present invention fulfills these needs and provides other significant advantages.

SUMMARY OF THE INVENTION

The improved fuel cap of the present invention comprises a fuel cap having a flexible ball sealing member mounted to the underside of the cap to engage with the upper end of a fuel filler neck to provide an improved seal between the fuel cap and the fuel filler neck.

Fuel filler necks such as described in U.S. Pat. No. 7,303,089 are at their top or upper end bounded by an annular shoulder. The shoulder extends about and defines an inlet opening which connects to the interior of the fuel tank. The shoulder has inner and outer margins forming the top of the shoulder. Located along the outer perimeter of the shoulder of the fuel filler neck are a plurality of protrusions for securing the cap to the fuel filler neck, sometimes called lugs. Such a plurality of protrusions are taught in U.S. Pat. No. 7,303,089.

The fuel cap has a top and a circumferential skirt joined to and extending down from the top. The fuel cap includes a plurality of recesses in the interior section of the cap along the circumferential skirt for coupling with the fuel filler neck as hereinafter described. The number of recesses is equal to the number of protrusions on the fuel filler neck. The protrusions mate with the recesses in the cap to secure the cap to the upper end of the fuel filler neck.

The flexible ball sealing member is a resilient and substantially compressible shaped sealing member with a form approximating half of a solid sphere. The flexible ball sealing member at its circular face is mounted on the underside of the cap. The radial dimension of the flexible ball is such that the flexible ball fits snugly inside fuel filler neck interior cylindrical surface. Sealing of the fuel tank is obtained where the flexible ball sealing member contacts the inner surface of the fuel filler neck. Additional sealing may be provided at the annular surface under the cap with a sealing element such as a gasket, o-ring or the like.

The flexible ball sealing member includes a section of tubing aligned coaxially to the circular symmetry axis of the fuel cap. The tubing penetrates the flexible ball at the lower portion. The upper portion of the tube penetrates the top portion of the cap as well, and is sealed thereto by suitable means such as an adhesive. Inset into the cap top portion and covering the end of the tube section is a metal disc which has a suitably low melting point, which is included as a meltout device.

In an alternate embodiment, the fuel cap of the present invention has a top and a circumferential skirt joined to and extending down from the top. The fuel cap includes screw threads formed in the interior portion of the cap along the circumferential skirt for coupling with a threaded fuel filler neck, wherein this alternate embodiment includes threads along the outer surface. The inward facing threads of the fuel cap mate with outward facing threads of the fuel filler neck to secure the cap to the upper end of the fuel filler neck. The fuel cap in this embodiment includes the flexible ball sealing member, including the tube and melt-out plug for relief of excessive pressure following an accident and possible fire.

The fuel cap of the present invention may optionally include a compression washer mounted about the vent tube, and secured loosely thereto by a pin or similar device mounted through the vent tube. This may be used with fuel filler necks made according to the present invention which include a ridge located circumferentially along the inner surface of the fuel filler neck. When the fuel cap fitted with the compression washer is installed on the fuel filler neck, the washer rests against the ridge of the fuel filler neck and is pushed up so that it compresses the flexible ball sealing member. The flexible ball sealing member expands radially against the inside surface of the fuel filler neck under the axial compression imparted by the washer. This radial expansion substantially improves the sealing properties of the fuel cap.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide an improved fuel cap that provides superior sealing, and security in the event of an accident.

It is another object of the present invention to provide an improved fuel cap that provides for inexpensive and simplified manufacture.

Other objects, features and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings wherein like characters of reference designate corresponding parts throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross sectional view of the fuel cap and a fuel filler neck.

FIG. 2 illustrates a top view of the fuel cap.

FIG. 3 illustrates a bottom view of the fuel cap.

FIG. 4 illustrates a cross sectional view of the fuel cap and a fuel filler neck as assembled.

FIG. 5 illustrates a cross sectional view of the fuel cap with compression washer, and a fuel filler neck.

FIG. 6 illustrates a cross sectional view of the fuel cap fitted with compression washer, and a fuel filler neck as assembled.

FIG. 7 illustrates a cross sectional view of the threaded embodiment of the fuel cap and fuel filler neck.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The improved fuel cap of the present invention comprises a fuel cap having a flexible ball sealing member mounted to the underside of the cap to engage with the upper end of a fuel filler neck to provide an improved seal between the fuel cap and the fuel filler neck.

Fuel filler necks have been described, as in U.S. Pat. No. 7,303,089, the teachings of which are herein incorporated. The fuel filler neck at its upper end or top is bounded by an annular shoulder. The shoulder extends about and defines an inlet opening which connects to the interior of the fuel tank. The shoulder has inner and outer margins forming the top of the shoulder. Located along the outer perimeter of the shoulder of the fuel filler neck is a plurality of protrusions or lugs. FIG. 1 shows a fuel filler neck 90 suitable for use with the present invention with lugs 92 at the upper outer circumferential surface.

The fuel cap of the present invention has a top portion 10 and a circumferential skirt portion 12 joined to and extending down from the top 10, as shown in FIG. 1. The exterior of the fuel cap may optionally include shapes 14, such as are shown in FIG. 2, for aesthetic purposes, or ergonomic purposes to enable the fuel cap to be readily grasped.

The fuel cap includes a plurality of recesses 22, shown in FIG. 3, in an interior section of the cap along the circumferential skirt 12 for coupling with the fuel filler neck as hereinafter described. The number of recesses 22 is equal in number to the number of protrusions on the fuel filler neck. The protrusions mate with the recesses 22 in the cap to secure the cap to the upper end of the fuel filler neck.

The flexible ball sealing member 30, or flexible ball, also shown in FIG. 1, is a resilient and substantially compressible sealing member with a form approximating half of a sphere. The circular face of the hemisphere of the flexible ball sealing member 30 is mounted on the underside interior of the cap. The radial dimension of the flexible ball 30 is such that the flexible ball fits snugly inside fuel filler neck interior cylindrical surface. Sealing of the fuel tank is obtained where the flexible ball sealing member 30 contacts the inner surface of the fuel filler neck 90. FIG. 4 illustrates the fuel cap as installed on the fuel filler neck 90. Additional sealing may be provided at the annular surface under the cap with a sealing element 25 such as an o-ring or gasket member or the like.

As shown in FIGS. 1, 3, 4, 5, and 6 the flexible ball sealing member 30 contains a section of tube 40 aligned coaxially to the circular symmetry axis of the fuel cap. The tube at the lower portion penetrates the flexible ball 30. The upper portion of the tube penetrates the top portion 10 of the cap as well, and is sealed thereto by suitable means such as an adhesive. Inset into the cap top portion and covering the end of the tube is a metal insert with a low-melting point, which is provided as a melt-out plug or device 50. The melt-out plug 50 may be round, or square or other suitable geometry. It is shown in FIG. 2 as round.

The cap may be used with some existing fuel filler necks, such as, for example, those described in U.S. Pat. No. 7,303,089, including fuel filler necks with anti-siphon structures incorporated therein as disclosed in that prior art. In particular, U.S. Pat. No. 7,303,089 describes a system of protrusions or lugs on the shoulder of the fuel filler neck and corresponding recesses on the interior of the cap for securing the cap to the fuel filler neck. The portion of the fuel filler neck relevant to the present invention is shown in FIGS. 1, 4, 5, and 6.

The fuel cap may be used with fuel filler necks wherein a small taper is incorporated in the inner surface of the fuel filler neck. The taper is such that the interior diameter of the fuel filler neck at the upper end is at its greatest, with the diameter decreasing slightly as the distance from the upper end increases. In this manner the closest fit and best seal is obtained where the cap is completely tightened. Generally the seal of the flexible ball sealing member 30 is improved under fluid pressure, where the flexible ball 30 is compressed against the fuel filler neck walls by the pressure.

The fuel cap of the present invention may optionally include a compression washer 80 mounted about the vent tube 40, as illustrated in FIG. 5, and secured loosely thereto by a pin 82 or similar device mounted through the vent tube 40. This may be used with fuel filler neck 90 made according to the present invention which includes a circumferential ridge 94 located along the inner surface of the fuel filler neck.

When the fuel cap fitted with the compression washer 80 is installed on the fuel filler neck 90, as illustrated in FIG. 6, the compression washer 80 rests against the interior circumferential ridge 94 of the fuel filler neck and is pushed axially up so that it compresses the flexible ball sealing member 30. The flexible ball sealing member 30 expands radially against the inside surface of the fuel filler neck 90 under the axial compression imparted by the compression washer 80. This radial expansion substantially improves the sealing properties of the fuel cap.

In an alternate embodiment, the fuel cap of the present invention has a top 10 and a circumferential skirt 12 joined to and extending down from the top. The fuel cap includes screw threads 24 formed in the interior portion of the cap along the circumferential skirt 20, as shown in FIG. 7, for coupling with a fuel filler neck which includes threads 96 formed along the outer perimeter of the shoulder. The inward facing threads 24 of the fuel cap mate with outward facing threads 96 of the fuel filler neck to secure the cap to the upper end of the fuel filler neck. The fuel cap in this embodiment includes the flexible ball sealing member 30 as disclosed herein, with or without the compression washer 80, including the tube 40 and melt-out plug 50 for relief of excessive pressure following an accident involving the truck.

The top portion of the cap 10, and the circumferential skirt may be formed of any suitable material, such as metal or plastic. If a plastic is chosen, should be selected from those plastic materials known in the art that are compatible with diesel, gasoline, or other fuels, and further have a softening temperature greater than the melting point temperature of the melt-out plug 50. The melt-out plug 50 also may be selected from those metal alloys or eutectics with the necessary properties, including a melting point in the temperature range required by applicable safety regulations.

The flexible ball member 30 may be formed of materials selected from rubber, or silicone, or other resilient and compressible elastomeric synthetic or natural materials well known in the prior art. The material must be compatible with diesel or gasoline or other fuel as used by the truck.

Although the foregoing embodiments of the present invention have been described in some detail by way of illustration and example for purposes of clarity and understanding, it will be apparent to those skilled in the art that certain changes and modifications may be practiced within the spirit and scope of the present invention. Therefore, the description and examples presented herein should not be construed to limit the scope of the present invention, the essential features of which are set forth in the appended claims. 

1. A fuel cap and fuel filler neck system comprising: (a) a fuel cap comprising a top portion, a circumferential skirt extending from said top portion, and a flexible hemispherical sealing member coupled to the underside of said fuel cap; and (b) a fuel filler neck where said flexible hemispherical sealing member closes and seals the inside opening of said fuel filler neck when the fuel cap is applied.
 2. The fuel cap and fuel filler neck system of claim 1, where (a) said fuel cap includes a vent tube that extends axially through said flexible hemispherical sealing member and through the top portion of said fuel cap; and (b) a metal melt-out plug covering the top portion of said vent tube.
 3. The fuel cap and fuel filler neck system of claim 2 where (a) said fuel filler neck is bounded by an annular shoulder at its upper end and has a plurality of protrusions along the outer perimeter of said annular shoulder; and (b) said fuel cap has a plurality of recesses in an interior section of the cap along the said circumferential skirt, where said plurality of recesses couple with said plurality of protrusions on said fuel filler tube.
 4. The fuel cap and fuel filler neck system of claim 3, where (a) a compression washer is movably attached to said vent tube, and (b) said filler neck includes a ridge on its interior circumferential surface, whereby said ridge causes said compression washer to compress said flexible hemispherical sealing member when said fuel cap is applied to said fuel filler neck.
 5. The fuel cap and fuel filler neck system of claim 2 where (a) said fuel cap supports screw threads in its interior face of the circumferential skirt; and (b) said fuel filler neck supports screw threads on its outer perimeter, whereby the fuel cap screw threads secure said fuel cap by coupling with the filler neck screw threads.
 6. The fuel cap and fuel filler neck system of claim 5, where (a) a compression washer is movably attached to said vent tube, and (b) said filler neck includes a ridge on its interior circumferential surface, whereby said ridge causes said compression washer to compress said flexible hemispherical sealing member when said fuel cap is applied to said fuel filler neck. 